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2. Measurement Process Characterization
2.6. Case studies
2.6.1. Gauge study of resistivity probes

Run gauge study example using Dataplot

View of Dataplot macros for this case study This page allows you to repeat the analysis outlined in the case study description on the previous page using Dataplot . It is required that you have already downloaded and installed Dataplot and configured your browser. to run Dataplot. Output from each analysis step below will be displayed in one or more of the Dataplot windows. The four main windows are the Output Window, the Graphics window, the Command History window, and the data sheet window. Across the top of the main windows there are menus for executing Dataplot commands. Across the bottom is a command entry window where commands can be typed in.

Data Analysis Steps
Results and Conclusions
Click on the links below to start Dataplot and run this case study yourself. Each step may use results from previous steps, so please be patient. Wait until the software verifies that the current step is complete before clicking on the next step. The links in this column will connect you with more detailed information about each analysis step from the case study description.
Graphical analyses of variability Graphs to test for:
  1. Wafer/day effect on repeatability (run 1)
  2. Wafer/day effect on repeatability (run 2)
  3. Probe effect on repeatability (run 1)
  4. Probe effect on repeatability (run 2)
  5. Reproducibility and stability

1. and 2. Interpretation: The plots verify that, for both runs, the repeatability of probe #2362 is not dependent on wafers or days, although the standard deviations on days D, E, and F of run 2 are larger in some instances than for the other days.

3. and 4. Interpretation: Probe #2362 appears as #5 in the plots which show that, for both runs, the precision of this probe is better than for the other probes.

5. Interpretation: There is a separate plot for each wafer. The points on the left side of each plot are averages at the wafer center plotted over 5 days; the points on the right are the same measurements repeated after one month to check on the stability of the measurement process. The plots show day-to-day variability as well as slight variability from run-to-run.

Table of estimates for probe #2362

  1. Level-1 (repeatability)
  2. Level-2 (reproducibility)
  3. Level-3 (stability)

1., 2. and 3.: Interpretation: The repeatability of the gauge (level-1 standard deviation) dominates the imprecision associated with measurements and days and runs are less important contributors. Of course, even if the gauge has high precision, biases may contribute substantially to the uncertainty of measurement.
Bias estimates
  1. Differences among probes - run 1
  2. Differences among probes - run 2
1. and 2. Interpretation: The graphs show the relative biases among the 5 probes. For each wafer, differences from the wafer average by probe are plotted versus wafer number. The graphs verify that probe #2362 (coded as 5) is biased low relative to the other probes. The bias shows up more strongly after the probes have been in use (run 2).
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